My feeling is that you should go and enjoy you time with colleagues because all the worrying you are doing will not make any difference.
Nagging feelings are understandable but not proof and without proof it would be unwise to accuse your wife – if she isn’t gambling then she might feel ‘what’s the point, he doesn’t believe me anyway?’ The addiction doesn’t need much provocation to rear its head.
I am trying to read between the lines and uncover what it is that is giving you the unsettled feelings. Has her behaviour changed? Are you finding yourself in the middle of arguments without knowing how you got there? Are you aware that she is telling lies about things that don’t matter?
Are you feeling more anxious because you are going away and this is what is giving you concern? I can’t tell you what to do but if you are away for only 2 days and you have no concrete evidence that you wife is gambling, it seems to me your anxiety has gone into overdrive.
What happened that has caused you to write this post because unless you have more than a gut instinct I cannot see why you cannot go and enjoy your trip which will surely do you good.